it was a big week for initial public offerings. here's an update on what they returned to investors. the biggest, dunkin brands, debuted wednesday on the nasdaq. it's up over 52% from its $19 i.p.o. price. teavanna gained 66% this week. chef's warehouse up 18% since the i.p.o., but biopharma company horizon pharmaceutical unchanged from its i.p.o. price of $9 per share. and that's tonight's "market focus." president obama took a break from the debt ceiling drama today to announce an historic agreement on new fuel efficiency standards. the deal will double overall fuel economy to 54.5 miles per gallon by 2025. that could mean filling up your gas tank every two weeks, instead of every week. diane eastabrook looks at some new technologies that could mean an even cleaner and more fuel- efficient ride down the road. >> reporter: if you check out the fuel economy of new cars and trucks, you might wonder if auto makers will be able to increase corporate average fuel economy to nearly 55 miles per gallon by the middle of the next decade. s